Abstract:
Background: According to Tear Film and Ocular Surface Society's Dry Eye Workshop II, the
precorneal tear film plays a crucial role in moisturizing the corneal surface and allowing for
an optically smooth corneal surface. In addition, as a result of imbalanced secretion of the
muco-aqueous phase of the tear film, the mucin layer traps shed epithelial cells, inflammatory
cells, and debris to form a mucous clot within the lower conjunctival fornix. Increased mucus
viscosity prevents moving mucus away via the punctum, which contributes to the development of
severe dry eye syndrome (DES). Our clinical experience argues that tear replacement therapy
alone can be not enough in the treatment of severe DES. N-acetylcysteine (NAC), a collagenase
inhibitor, has been widely employed clinically as a mucolytic agent. Foreign literature is scant
on the use of NAC as an anti-inflammatory, mucolytic, detoxicant and anti-oxidative agent in
the treatment of DES.
Purpose: To assess the efficacy of topical 5% N-acetylcysteine as a part of multicomponent
treatment for severe DES associated with increased mucus production.
Material and Methods: We reviewed records of 15 patients examined and treated for severe
DES. At baseline, there was biomicroscopic evidence of mucous discharge in the conjunctival
fornix, corneal epitheliopathy in the form of punctate fluorescein staining, and desquamated
epithelium, which was consistent with severe DES.
Results: At admission, mean Schirmer’s test value and tear break-up time (TBUT) were 3.4
mm (range, 2 to 6 mm) and 4.2 s (range, 2 to 8 s), respectively, and conjunctival impression
cytology revealed focal epithelial degeneration. Topical 5% NAC was administered 4 times
daily for 3 months as a part of multicomponent therapy for severe DES.
After 3 months of topical 5% NAC, 86.6% of patients noted good tolerance to the drug and
improvement of subjective symptoms, and there was biomicroscopic evidence of a reduced
amount of mucus in the conjunctival fornix and decreased epithelial desquamation. Mean
Schirmer’s test and TBUT values increased to 5.0 ± 1.7 mm (mean ± SD) and 6.4 ± 1.7 s,
respectively. Conjunctival impression cytology showed the presence of mucoid substance;
diffused, differentiated epithelial cells without signs of degeneration; and an adequate
superficial conjunctival epithelial cell layer.
Conclusion: Topical 5% N-acetylcysteine 4 times daily as a part of multicomponent treatment
showed a substantial mucolytic effect for severe DES with apparent thick mucus discharge in
the conjunctival fornix and resulted in the development of an adequate superficial conjunctival
epithelial cell layer. Findings of this study allow us to recommend topical 5% N-acetylcysteine
for severe DES patients with increased viscous mucous discharge in the conjunctival fornix.
